1. Field
This invention relates generally to the field of wireless communications and more particularly to a method of providing at least limited telephone service for mobile terminals in the event of a failure on a signaling link between a mobile switching center in which the mobile terminals are registered and either a home location register or a service control point (sometimes referred to as a signal control point).
2. Description of Related Art
The international standards document TIA/EIA/IS-41-D sets forth a network architecture for providing mobile telecommunications and networking. Commercial deployments of mobile telecommunications networks in compliance with IS-41 have occurred in North America and elsewhere. Such systems include a wireless communication network infrastructure (e.g., Code Division Multiple Access (CDMA) cellular telephone network) which includes a multitude of base transceiver stations and associated antennae for communicating over an air interface with roaming mobile terminals, base station controllers, and mobile switching centers (MSC) which perform switching operations to direct calls to a mobile terminal via a base station controller and a base transceiver station.
Many deployments of IS-41 compliant systems use advanced intelligent networks (such as Signaling System 7 (SS7) networks) to carry signaling and control messages between an MSC and various other signaling points, such as a Home Location Register (HLR) and Service Control Points (SCPs). For example, the MSC may obtain profile information for a roaming mobile terminal from the HLR, such as which features the mobile terminal is allowed to use and whether the mobile terminal can place certain types of calls. As another example, in many situations the user of a mobile terminal is a subscriber to a pre-paid calling plan, and when an MSC is serving a pre-paid mobile terminal, the MSC needs to provide information to an SCP dedicated to pre-paid mobile terminals, e.g., for billing or accounting functions for such subscribers.
It so happens that the communication link between a serving or terminating MSC and the nodes on an intelligent network such as an HLR or pre-paid SCP fails. One example of such failure is where the signaling path between the MSC and the HLR or pre-paid SCP includes a satellite link, and the satellite either goes down for service or maintenance, a malfunction of the satellite occurs, or the orbital path of the satellite is such that it goes out of range of an antenna transmitting signals to the satellite or receiving signals from the satellite.
There is a need in the art for a method of operating an MSC such that when a signaling path between the MSC and a HLR or pre-paid SCP fails, the MSC may continue to provide at least limited telephone service for those mobile terminals that are registered with the MSC, in both serving and terminating capacities. This invention meets that need.